1. Field of the Invention
The present invention relates to the field of machine tools and more particularly to modifications with which high-speed machining of parts can be achieved under the best conditions.
2. Discussion of the Background
High-speed machining of parts in a machine tool generally takes place using a tool driven rotationally by the motor shaft of an electric spindle installed in a slide, which itself is mounted to be movable by translation along three axes X, Y and Z.
A machine tool is classically provided with three main working stations, to wit:
a machining station proper, provided with the tool driven rotationally by the motor shaft of the electric spindle and shaping the part to be machined, PA1 a drive station situated upstream from the machining station and comprising an assembly of mechanisms that ensure in particular the X, Y and Z displacements of the slide of the electric spindle as well as the supply of power to the electric spindle for rotation of its tool-carriage shaft, PA1 and a control station cooperating with the drive station and as a function of a program of instructions preestablished to take charge of the different phases of machining of the said part. PA1 by virtue of its lubricating nature, does not cause corrosive attack of the mechanisms, PA1 by virtue of its fluid nature is capable of filling the gap, even of minimum size, necessary for assembly of the electric spindle, PA1 by virtue of its viscosity is a good damping agent.
The Applicant has observed, during high-speed machining, that the rotation of the drive shaft of the electric spindle at extremely high speed, the contacts between the tool and the part to be machined, and the translational displacements of the slide of the electric spindle in the X, Y and Z directions are responsible in combination or individually for substantial vibrations of the assembly comprising slide and electric spindle. These vibrations are due in part to the fact that the operation of insertion of the electric spindle into the slide necessitates some mounting play between their contact surfaces, since clamping is takes place only on the front portion of the electric spindle, while the rear body of the electric spindle is not held directly in position. During the machining operations, therefore, vibrations develop which have harmful consequences for the internal elements of the electric spindle, resulting in shorter service life thereof.